Dental engine



B. M; WILKERSON.

' Dental-Engine. v

No. 228.14 9. Patent ed May 25, I880.

UNITED STATES PATENT Orricn.

MARYLAND.

DENTAL ENGINE.

-'SPEGIFIGATION forming part of Letters Patent No. 228,149, dated May25, 1880.

Application filed March 4, 1879.

To all whom it may concern:

Be it known that I, BASIL M. WILKERSON, of Baltimore city, State ofMaryland, have invented certain new and useful Improvements in DentalEngines; and I hereby declare the same to be fully, clearly, and exactlydescribed as follows, reference being had to the accompanying drawing,in which the device is illustrated in side elevation.

My invention relates to dental engines operated by means of a treadle,and designed to communicate motion to a flexible cableor rigid shaft towhich a drill-point, disk, or other in strument is secured 5 and itconsists in such' an engine embodying novel details of construction,whereby important results are attained, as hereinafter set forth.

With that class of engines having a rigid shaft to which the hand-pieceis securedeither immediately or through the medium of a short flexiblesection of shafting, it is practically indispensable that the verticalshaft carrying the driven pulley shall be capable of a rocking motion,and for a reason that is obvious. While not absolutely indispensable,this rocking feature is very important in that class of engines in whicha flexible cable is used, and in either case it has heretofore beenattained by pivoting the vertical shaft at or near the fly-wheelbearings and maintaining it normally in a vertical position by means ofa spring.

It has been found impossible heretofore, however, to hold the shaft witha reasonable degree of stability while still admitting of the desiredfacility in rocking it. The salient feature of my invention consists instanding this shaft upon a somewhat extended base-placin g it, in aword, in a condition of stable equilibrium, or in such position as whenmoved its center of gravity is raised.

In the accompanying drawing, A is the flywheel, driven in the usual wayby a treadle, (not shown,) and mounted upon a shaft, a, journaled in abase, B. The latter is extended upward above the shaft and terminates ina crosspiece, D, forming a T, as shown. Centrally in the cross-piece issecured a pin, b, and equidistant at either side are other pins, 0 c.

The vertical shaft 0 is secured below to a saddle, c, which extends overthe fly-wheel at either side and rests upon the pins 0 c, which extendthrough slots (1, formed in the saddle.

It is to be understood that the construction of the parts on theopposite side of the wheel to that shown in the drawing is identicalwith that illustrated.

Pins (1 are secured in the saddle at either side and beyond the slots d,each of which latter is formed in the arc of a circle described aboutthe upper end of the other as a center. A spring, D, is sprung under thecenter pin, 1), and over the pins (1, as shown, hold-ing the saddle downuponthe pins 0. The cap-piece E is mounted upon the upper end of theshaft 0, and contains a pulley driven by a belt, 6, from the flywheel A.To the spindle of the driven pulley is attached the cable H, carryin gthe hand-piece I. A spring, K, is attached at one end to the cap-pieceE, and is provided at the other with a ring, through which the cablepasses, the spring being designed to sustain the cable and prevent itsfracture as the hand-piece is allowed to fall.

7 It will be noticed that the entire superstructure above the fly-wheelrests upon a base whose area is the quadrilateral described by linesjoining the pins 0. As a consequence the device is in a state of stableequilibrium until the perpendicular let fall from its center of gravityfalls without this base when the shaft is rocked. This rocking issomewhat resisted by the spring D, which brings the device back to avertical position even when dis- .turbed to the ultimatelimit affordedby the slots d. As the shaft is rocked it moves upon one of the pins 0,and may be so rocked until the bot-tom of the opposite slot brings upagainst the other pin.

Inasmuch as the motion of the device is not about the center shaft, a,it might seem that upon rocking the shaft unequal tension would bebrought upon the belt a,- but the peculiar disposition of the pivots cis such that practically this is not the case.

In the drawing the heavy dotted line a represents what would be the pathof the top of the pulley did it pivot upon the shaft a, and the finedotted lines 1 2 l 3 show what is actually its path, pivoting as it doesupon the pins d d. The variation is at its maximum at the points 2 and3, and even there it is utterly insignificant, as it amounts only toabout: rad. cos. of angle 0' 1 b, as the angle is so small its radiusand cosine may be considered equal, so

the tension of the belt is practically not affected by the rocking ofthe shaft. When used with a flexible shaft or cable it is not essentialthat the shaft shall be capable of rocking to both sides of theperpendicular, as the cable will not transmit a thrust; but thedescribed construction is equally as convenient and more symmetricalunder-allcircumstances.

What I claim is- 1. A dental engine having its vertical shaft mountedloosely upon the pedestal on an extended base, and being thereby in acondition of stable equilibrium, substantially as described.

2. A dental engine having its vertical shaft capable of oscillationlaterally, and normally retained in a vertical position upon an extendedbase by means of a spring, substantially as described.

3. A dental engine having its vertical shaft 20 normally retained in avertical position by means of a spring, and capable of oscillationlaterally upon pivots located upon either side of the fly-wheel and ateither side of the perpendicular through the fly-wheel shaft, as set 25forth.

4. In combination with the flywheel and vertical shaft, the base-piecehaving pins 1) c and the slotted saddle c and spring D, substantially asdescribed.

BASIL M. WILKERSON.

Witnesses:

R. D. WILLIAMS, J. C. GITTINGER.

